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    <title>Document</title>
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    <script type="text/javascript">
        1.
        // function A() { }
        // A.prototype.n = 1
        // var b = new A()
        // A.prototype = {
        //     n: 2,
        //     m: 3,
        // }
        // var c = new A()
        // console.log(b.n, b.m, c.n, c.m)//1,undefined,2,3


        2.
        function Foo() {
            Object.prototype.a = function () {
                console.log('可访问a')//可访问a
            }
        }
        Function.prototype.b = function () {
            console.log('可访问b')//
        }
        var foo = new Foo()
        foo.a();//
        foo.b(); 
        Foo.a(); 
        Foo.b();


    </script>
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